I'd give Craig Nettleton a call at Auto Solutions - he's an auto locksmith who comes to some of our annual meets and sorts out keys for some of us -
try him on 07900-600548
or his website is http://www.autosolutions-autolocksmi...contact-us.php
He will probably know straight away if there are any issues

I've done this for my 2006 S8 which is keyless, for one key just buying a case, and the other sent away for a rebuild, and there were no problems. Everything seems to be on the board. The aftermarket cases don't have quite as nice a 'feel' as the originals but they're OK.

Yes, I just get the cases from Aliexpress or ebay.
Quality varies and sometimes the original metal key blade is not 100% great fit in th new case and also some come with new gaskets and some do not. Try and look on the photos for the seal around the edge.
I wish someone could get the newer key working or someone make a new style case for older internals - CHINA I AM LOOKING AT YOU!

I'd actually like to have a go at upgrading but don't fancy risking it with one key.

May try it with a second hand key off eBay as a project!

Iíve been thinking about doing this for a while.

Did it with my old e46ís key. Was pretty decent, but like others have mentioned the knockoff blanks and cases arenít OEM quality. Also when using the new blank, I really had to twist the arm of the key cutter to consider doing it for me. Which was odd.